Crushing mill



3 Sheets-Sheet mvzNToR ERN 5T cvRT LDE SCHE ATTORNEY 1931- E. c. LJOESCHE GRUS'HING MILL Filed April 11, 1928 :s Sheets-Sheet 2' ATTORNEY Dec. 29, 1931; E. c. LOESCHE CRUSHING MILL Filed April 11. 1928 s Shets-Sheet 3 mvam'og ERNS CURT LOESCHE Patented Dec. 29, 1931 UNITED STATES ERNST GUR'I. LOESCHE, OF BERLIH-LANKWITZ, GERMANY GRUSHING MILL Application fled Apri1 11, 1928, seri ai no.

My invention relates to improvements in crushing mills, and more particularly in mills for crushing coal or similar material comprising a rotary dish or table and rollers bearing thereon. Oneof the objects of the improvements is to increase the efliciency of mills of this type. I have found that the efliciency of the mill is at its-maximum if there is a definite ratio between-the diameters vided with rings adapted to be'placed on the.

upper margin the dish. p

Ordinarily the rolls are disposed on arms for-enlarging the surface of ro'cl'ringly mounted on the-frame work of the mill and they are formed with spherical crus ng surfaces corresponding to the surface of the dish. Instead of mounting the rolls on arms I may construct the rolls in the form of balls loosely engaged-by arms holding. the same in position and adapted to be rotated by their frictional engagement with the surface of the dish or the material carried thereby. To reduce friction I ,pre-- fer to provide the said' arms with rolls providing an anti-frictional support for the balls. 5 w p In mills of the class referred to the ground .material is delivered from the margin of the dish, and means are provided for producing a blast of air carrying the powdered material away from the dish, the coarser particles falling back into the dish for being again subjected to the grinding action of the rolls. The blast of air is supplied to thecasing of the mill ybelow the rotary dish, and it is directed upwardly therefrom and around the circumferenceof the dish. I have found that 269,117. at in Germany October 23,1926.

the efliciency of the mill is improved if the cross-sectional area of the passage of the air flowing from the bottom side of the dish upwardly remains substantially constant. The said passage is provided by the annular space provided below and around the dish, the air being supplied substantially at the middle of the said annular space. Therefore, the circumferential dimension of the annular passageis gradually increased fromthe center of the dish to the upper circumference thereof, and in order to have a passage of substantially uniform cross-sectional area it is necessary to reduce the radial dimension' of the annular passage from the center to the circumference of the dish at the rate of the increase of the circumferential dimension. I have found that when thus constructing the annular passage the blast ofair which is-ordinarily delivered into the saidpassage in tangential direction is adapts ed to keep the passage clear even of coase material, the blast of 'air carrying the said coarse material falling from the marginof the dish upwardly and returning the same into the dish or into a shifting apparatus provided above the dish.

' In mills of the class referred to it is frequently desirable to examine the rolls and the bearings thereof. Another object of the improvements is'to provide a mill in which the rolls can be readily removed from the casing'enclosing the rotary dish and the rolls without special machinery, and with this ob-' ject in view my invention consists in so combining the rolls and their bearings with lids for' closing holes made in the casing of the mill, that the rolls can be rocked out of the casing through the. said holes while simultaneou'sly removingthe lids.

, Particularly in case'of heavy mills it is objectionable that the rolls are liable to roll-directly on the surface of the dish without material to be crushed being interposed betweenithe same and the dish. Therefore, in order to prevent direct contact between the rolls and the surface o'fthe dish I provide stop members adapted to hold the rolls a certain distance away from the surface of the dish. Preferably, the said stop members are adjustable.

Other objects of the improvements will appear from the following description.

For the purpose of explaining the inven tion several examples embodying the same have been shown in the accompanying drawings, in which the same letters of reference have been used in all the views to indicate corresponding parts. In said drawings,

Fig. 1 is a sectional elevation showing the mill,

Fig. 2 is a sectional plan view taken on the line 22 of Fig. 1,

Fig. 3 is a detail sectional elevation showing a modification of the means for supplying the material to the mill,

Fig. 4 is a sectional elevation showing a modification of the rotary dish or table and a crushing ball cooperating therewith,

Fig. 5 is a top plan view of Fig. l,

Fig. 6 is a sectional elevation showing another modification of the rotary dish or table,

Fig. 7 is a detail sectional elevation showing a modification of the means for enlarging the active surface of the dish.

Fig. 8 is a sectional elevation of a part of the casing of the mill, a rotary table or dish, and a rockably mounted crushing roll,

Fig. 9 is a sectional elevation showing a modification of the construction of the crushin roll and the supporting means therefor,

*ig. 10 is a detail sectional elevation looking from the left of Fig. 9 andshowing the manner of mounting the crushing roll on the lid, and

Fig. 11 is a sectional elevation showing ankeyed to a shaft 10 and a pulley 10. To the top part of the shaft 8 a table or dish 11 is secured which is curved upwardly at its margin thus providing a concave top face. The top face of the dish 11 is engaged by one or more rolls 12 bearing on the concave marg1nal part of the dish 11 and having a configuration corresponding to the said concave part. Each of the rolls 12 is rotatably mounted on an arm 13 rockingly mounted at 14 on a member 15 rockingly mounted on a lug 16 formed on the part 2 of the casing of themachine, and the member 15 1s fixed to or made integral with a lid 17 closing an opening 18 made in the wall of the top part 3 of the casing, the dimension of the said opening 18 being such that the roll 12 can be rocked out of the casing. The arm 13 is'formed with an extension 19 formed with a hole, and through the said hole a rod 20 fixed to the arm 15 is passed. To the screwthreaded outer end of the said rod 20 a nut 21 is screwed which provides a support for a coiled spring 22 bearing on the extension 19 of the arm 13 and tending to force the roll 12 towards the dish 11. One or two nuts 23 are provided on the bolt 20 at the side f the extention 19 opposite to the spring 32, and the said nuts are adjustable on the bolt. The nuts 23 provide an abutment for the arm 13 for limiting the movement of the roll 12 towards the dish 11. Thus the nuts can be set in position for holding the roll 12 a suitable'distance away from the surface of the dish 11 for preventing direct contact of the rolls and the surface of the dish 11.

There is only one roll shown in the drawin s for the purpose of clearness, but preferably several rolls are used.

The material to be ground is supplied to the casing through a pipe 25 including a feeding member in the form of a rotary wheel 26 having radial arms 27, the material being fed through the said pipe to the part of the casing below the dish 11 and being carried upwardly by a blast of air.

The said blast of air is supplied through a pipe 30 opening tangentially into the part 2 of the casing below the dish 11. Thus the blast of air is whirled around within the space provided between the bottom part of the dish 11 and the wall of the part 2 of the casing and it rises upwardly from the said chamber into the part 3 of the casing, from whence it escapes through a tubular outlet 31. I have found that the efiiciency of the blast of air is particularly high if the cross-sectional area of the passage 32 remains constant from its bottom or central part to its top or circumferential part. Therefore the radial dimension of the said chamber isgradually reduced from its bottom'part to its top part. If the radius of the annular passage at the top part is r and at another part 7 and the breadth of the passage at the said points is respectively m and m the circumferential areae are at the ratio r 1*. Therefore, in order to have uniform cross-sectional areae throughout the length of the passage, the breadth of the passage must be reduced from the bottom part to the top part according to the proportion r :r =w ::v.

In the operation of the apparatus the blast of air rising from the passage 32 carries away the powdered material through the outlet 31. In constructions now in use the blast of air produces whirls on the central and top part of the dish, so that the material being crushed is liable to be carried away. Therefore, in order to prevent the action of the blast of air on the material being'crushed provision is made for causing the blast of air to flow alongside the circumferential wall of the part 3 of the casing. In the example shown in upwardly along the wall of the casing, and

rockable gates 38. The inner diameter of the part 3 of the casing is equal to or smaller than the diameter of the top part of the dish.-

In the operation of the mill the material to be ground, for example coal, is supplied to the dish, 11, which is rapidly rotated. Therefore the rolls 12 crush the coal which gradually rises from the center of the dish to the circumference from whence it is thrown outwardly by centrifugal action. Through the pipe 30 a blast of air is admitted to the annular passage 32, which blast of air rises up wardly around the circumference of the dish and carries away the ground material delivered from the dish. The heavy particles which have not been sufficiently ground fall back into the dish 11, while the finer particles are carried upwardly by the blast of air and through the annular passage 39 provided between the cylinder 35 and the wall of the part 3 of the casing. Thus the blast of air moves it has no objectionable action on the material being ground. The separation of' the coarser particles of the material is assisted by the tapering form of the bottom part of the wall of the casing 3, by which an inward direction is imparted to the said particles. The fine particles of the material are carried upwardly and deflected inwardly and through the passages provided between the vanes 36. By the said deflection a further separation of coarse particles is accomplished. By reason of the inclined position of the vanes 36-tl1e blast of air is delivered into the cylinder in tangential direction, so that the separation of the coarser particles is continued by centrifugal action, the air and finest particles of the material being delivered through the outlet 31, while the'separated particles fall into the funnel 37 from which they are intermittently removed after opening the gates 38. The material delivered from the funnel 37 falls on the dish 11 for being again ground.

If it is desired to examine the rolls 12 the rockable lids 17 are rocked outwardly together with the rolls 12.

The diameters of the rolls 12 and the dish 11 are at the ratio of 1: 2, 5 or less. I have found that thereby the efiiciency of the mill is atits maximum.

In Fig. 3 I have shown a modification of the means of supplying the material to the rotary dish 11. As shown, the said dish is in the form of a funnel or chute. 251 ending at a part above the dish 11, so that the ma)- ification of the rolls.

terial to be crushed is directly supplied to the top face of the said dish. In Figs. 4 and 5 I have illustrated a modfrgures the rolls are in the form of balls 40 loosely rolling on the top face of the dish 11.

For holding the balls in position when rotating the dish 11, arms 41 are fixed to the 'wall' of the casing 3, which arms are preferably provided with anti-f-riction rollers 42 located in position for engaging the balls 40.

For grinding very tough material I extend the dish 11 at its upper margins by placing thereon one or more rings 44, as is shown in Fig. 6 In the modification shown in Fig. 7 a single ring 441 is provided, which is fixed to the circumferential face of the dish 11 by means of screws 442 passed through vertical slots443. By reason of the said slots the ring 441 can be set in different positions vertically for more or less enlarg ing the' active surface of the dish 11.

In Fig. 8 I have shown a modification in which the arms 45 on which the rolls 46 are rotatable are made integral with arms 47 rockingly mounted on lugs 48provided on the casing of the apparatus. To the lid 49 a bolt 50 is secured which is passedthrough a'bore of the arm 47 and carries at its outer end a disk 51 and a nut 52 providing a support for a coiled spring 53 acting on the arm 47 and tending to push the roll 46 towards the surface of the dish 11. For examining the roll 46 the whole system including the arm 47, the lid 49 and the roll 46 is rocked outwardly into the position shown in dotted lines.

The means for arresting the roll 12 in a position away from the surface of the dish 11 and consisting in the example illustrated in Fig. 1 of the nuts 23 may also be provided in other mills in which the rolls are forced in contact with the dish by centrifugal force, in which case bails maybe provided for holdingi1the rolls away from the surface of the dis In the modification shown in Figs. 9 and 10 the lid is fixed to the casing 71 of the mill by means of screws 72, and it has a pivot formed with a hole through which a bolt 76 carrying a nut 77 is passed, the said bolt being jointed to the lid 70 at 78. Between the rear end of the arm 74 and the nut 77 a coiled spring 79 is placed on the bolt 76, Which spring tends to force the crushing r0117 5 on the dish 11. For removing the roll fromthe mill the screws 72 are unscrewed, whereupon the lid and the roll are simultaneously removed from the mill.

In the examples so far described the material delivered from the dish 11 is carried upwardly by the blast of air, so that special As shown in the said means for removing the material from the passage 32 may be dispensed with. In Fig. 11 I have shown a modification in which mechanical means are provided for removing the material falling from the dish downwardly and returning the same on the dish. The dish 55 is mounted substantially in the same way as has been described with reference to Figs. 1 and 2. The blast of air is delivered into the casing'56 through an annular pascage 57. Between the circumference of the dish 55 and the wall of the casing 56 a comparatively broad annular passage 58 is provided, so that the blast of air rising from the said passage is comparatively weak, which may be desirable in some cases for having a good sifting action. Thus a part of the coarse material may fall into the said annular chamber, and in order to remove the material from the bottom of the said chamher I provide the dish 55 at its circumference with one or more buckets 59 adapted to collect the material from the bottom and to throw the same upwardly and against the tapering wall of the casing 56. Thus the material is again thrown into the blast of air and the fine particles are carried away by the said blast, while the coarser particles, which are directed inwardly by the tapering wall of the casing 56 and the direction of the blast of air are returned on the dish 55.

The construction of the rolls 60 may be the same as that described with reference to Fig. 1. But as shown, they are not constructed for being rocked outwardly, but they are rockingly mounted on lugs 61 rising from the wall of the casing 56, springs 62 being provided for forcing the roll 60 on the surface of the dish 55.

I claim:

A mill, comprising a casing having an opening, a removable lid for closing said casing, a dish rotatable around a vertical axis and mounted within said casing, a crushing roll bearing on said dish and a rockably mounted arm on which said roll is mounted and extending through said hole into said casing and forming a unit with each single lid, said roll and lid being mounted for being removed from the casing as a unit.

In testimony whereof I have afiixed my signature.

ERNST CURT LOESCHE. 

